"Colin Swift" ) writes:
Hi,

I've been given a wavefront travel case Theremin to repair.... seems the
power supply is dead, it has a 3 pin DIN connector alas I am not 100% sure
as to what the voltages should be on these pins? Is there anyone out there
who knows? I tried e-mailing the company however haven't received a reply.

So far the voltages measured on the pins on the din connector are -12, 0
and -0.71V - I guess the latter pin should be +12v. The power supply that
came with the unit is an adapted computer psu with output voltages of +/-12v
and +5v - but only 3 outputs are used. Looking at the resistor to the 'on'
LED (220 ohms) I am now 90% sure that there should be +12V and not +5V on
this line. I just want to be 100% sure if possible. The transformer is one
of those impossible to open things (sealed - cant see any screws) and as its
not mine, I'm not overly keen to take a hacksaw to it.

You do realize that those computer power supplies expect a decent load on
the output(s)? If they aren't loaded properly, you won't see the voltages
it is supposed to supply.

Before assuming the power supply is bad, you'd better make sure it is properly
loaded.

And if the power supply is bad, it's likely simplest to replace the whole
thing. It surely can't be "adapted" very much.

If the power supply is bad, you can't really assume anything. If you think
it's adapted, then you really need to know what voltages it was supposed
to put out.

Micahel

Anyway, hope someone out there knows, tho I guess its a long shot so
thanks in advance for your help.

Colin